Current way was expecting return values that are not present in slaves

Comments, trailing spaces, dead code

This is a squash merge of 'resiliency-testing' branch when
the HEAD of this branch was f725c81d7d69.

The merge was done by Antoine Catton.

This reverts commit fdb2b87b.
This breaks erp5 test runner (maybe it does not accept IPv6 in SQL
connection strings).

Also, make it optional.

Unused since egg bump from commit 80bfb5e0 .

It is not used in xwiki and lamp, does not work out of the box in erp5, and
prevents erp5 from moving further toward IPv6 support.
Do not drop its component SR and recipe just yet, as it might find some
use in the near future.

Based on work by Romain Courteaud <romain@nexedi.com>.

Mainly to get erp5.util.taskdistribution fixes.